Circuit board and conductive pattern structure

ABSTRACT

A circuit board includes a first conductive layer, a second conductive layer, and a first insulating layer disposed between the first conductive layer and the second conductive layer, wherein the first conductive layer includes a signal line, the second conductive layer includes a ground line, and the ground line of the second conductive layer includes a pattern area patterned in a meander shape.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.15/198,679 filed on Jun. 30, 2016, which claims the benefit under 35 USC119(a) of Korean Patent Application No. 10-2015-0140502 filed on Oct. 6,2015, in the Korean Intellectual Property Office, the entire disclosuresof which are incorporated herein by reference for all purposes.

BACKGROUND 1. Field

The following description relates to a circuit board and a conductivepattern structure.

2. Description of Related Art

A circuit board may be generally classified as either a microstripcircuit board or a stripline circuit board based on the type oftransmission line used in the circuit board and the electromagneticfield produced by the circuit board. Both the microstrip and thestripline circuit board have a ground and an electrical field formed bya signal line. In these circuit boards, the electrical field generatedby the circuit board influences the characteristic impedance of thecircuit board.

In either a microstrip circuit board or a stripline circuit board, theimpedance characteristics of the circuit board are generally determinedby a line width and thickness of the signal line, a height between thesignal line and the ground, a dielectric constant of a medium that formsthe insulating layer, and the like. However, in accordance with anindustry trend toward producing thinner and portable electronicproducts, a thickness of the insulating layer tends to be reduced whenthe circuit board to be included in the electronic products is designed.The reduction in the thickness of the insulating layer may result in thecharacteristic impedance of the circuit board being reduced beyond adesired value.

In order to prevent the impedance reduction, a method for adjusting theline width or the thickness of the signal line is proposed. However,when the line width or the thickness of a signal line is adjusted tocontrol the impedance of the circuit board, while the impedance may bematched to the desired value, a transmission loss may inevitably occur.Further, due to the adjustment to the line width and the thickness ofthe signal line, the freedom to design a layout for the circuit elementmay be also significantly compromised.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

In one general aspect, a circuit board includes a first conductivelayer, a second conductive layer, and an insulating layer disposedbetween the first conductive layer and the second conductive layer,wherein the first conductive layer includes a signal line, the secondconductive layer includes a ground line, and in a corresponding areaprovided with the signal line and the ground line, the ground line ispatterned so that changing a position of the signal line within thecorresponding area results in an impedance change of 1 Ω or less.

The ground line may include a pattern area patterned in a meander shape.

A shape of unit pattern of the ground line under the signal line may besubstantially the same regardless of a position of the signal linewithin the corresponding area.

In the corresponding area provided with the signal line and the groundline, a return path of the ground line corresponding to the signal linemay remain substantially the same regardless of a position of the signalline.

The ground line may include a pattern area patterned in an obliquemeander shape.

The second conductive layer may further include dummy patterns, and thedummy patterns may not be connected to the ground line.

In another general aspect, a circuit board includes a first conductivelayer, a second conductive layer, and an insulating layer disposedbetween the first conductive layer and the second conductive layer,wherein the first and second conductive layers each include a signalline and a ground line, and outer unit patterns are disposed along anedge portion of the ground line, and inner unit patterns are disposedbetween the outer unit patterns, the outer unit patterns connecting theinner unit patterns to one another.

The outer unit patterns may have an opened curve shape, and the innerunit patterns may have an obliquely inclined shape, the outer unitpatterns and the inner unit patterns being connected to each other toform a return path of the ground line.

The inner unit patterns may have an obliquely inclined shape with aconstant width.

The inner unit patterns may be disposed with a constant intervaltherebetween.

The inner unit patterns may include obliquely inclined stripes alignedalong substantially the same direction.

The inner unit patterns may include obliquely inclined stripes forming azigzag shape.

The second conductive layer may further include dummy patterns, and thedummy patterns may be disposed between the outer unit patterns and theinner unit patterns.

In another general aspect, a circuit board includes a first conductivelayer, a second conductive layer, and a first insulating layer disposedbetween the first conductive layer and the second conductive layer,wherein the first conductive layer includes a signal line, the secondconductive layer includes a ground line, and the ground line of thesecond conductive layer includes a pattern area patterned in a meandershape.

The pattern area of the ground line may be patterned in an obliquemeander shape.

The general aspect of the circuit board may further include a thirdconductive layer and a second insulating layer disposed between thethird conductive layer and the first conductive layer, wherein the thirdconductive layer includes a second ground line, and the second groundline includes a pattern area patterned in a meander shape.

In another general aspect, a conductive pattern structure includes aconductive path in which conductive patterns are connected to eachother, wherein the conductive patterns include: outer conductivepatterns having an opened curved shape disposed along an edge portion ofthe conductive path, and inner conductive patterns having an obliquelyinclined shape disposed between the outer conductive patterns.

In another general aspect, a circuit board includes a first conductivelayer including a signal line, a second conductive layer including aground line, and an insulating layer disposed between the firstconductive layer and the second conductive layer, wherein the groundline includes a pattern area in which the ground line intersects thesignal line in a plan view by making a plurality of passes across thesignal line, and a current direction in the ground line alternates inthe plurality of passes across the signal line.

The plurality of passes across the signal line may include a first passand a second pass across the signal line, and the current directionacross the first pass may be configured to be substantially opposite tothe current direction across the second pass.

The ground line may be patterned in a meander shape in the pattern area.

The current direction in the ground line may not change when a positionof the signal line changes within a corresponding area of the groundline.

A conductive pattern structure for a circuit board includes outerconductive patterns disposed along an edge portion of a pattern area,and inner conductive patterns disposed in the pattern area and connectedto one another via the outer conductive patterns to form a conductivepath having a meander shape.

The inner conductive patterns may include obliquely inclined conductivestripes that are connected via the outer conductive patterns to form anoblique meander shape.

The inner conductive patterns may have a zigzag shape, a curved waveshape, or an obliquely inclined shape and may be connected to each othervia the outer conductive patterns to form the meander shape.

The inner conductive patterns may include a first inner conductivepattern and a second inner conductive patter, and the first innerconductive pattern and the second inner conductive pattern may bedisposed parallel to each another such that a current direction throughthe first inner conductive pattern and a current direction through thesecond inner conductive pattern are opposite to each other.

Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 schematically illustrates an example of a circuit board used inan electronic component.

FIG. 2 illustrates a ground part of an example of a circuit boardaccording to FIG. 1.

FIG. 3A is a cross-sectional view schematically illustrating an exampleof a circuit board.

FIG. 3B is a cross-sectional view schematically illustrating anotherexample of a circuit board.

FIG. 4A is a cross-sectional view schematically illustrating anotherexample of a circuit board. FIG. 4B is a cross-sectional viewschematically illustrating yet another example of a circuit board.

FIG. 5 is a plan view schematically illustrating an example of aconductive layer having a ground line.

FIG. 6 is a plan view schematically illustrating an example in which adummy pattern is applied to a conductive layer having a ground lineaccording to FIG. 5.

FIG. 7 is a plan view schematically illustrating another example inwhich a dummy pattern is applied to a conductive layer having a groundline according to FIG. 5.

FIG. 8 is a plan view schematically illustrating another example of aconductive layer having a ground line.

FIG. 9 is a plan view schematically illustrating an example in which adummy pattern is applied to a conductive layer having a ground lineaccording to FIG. 8.

FIG. 10 is a plan view schematically illustrating another example inwhich a dummy pattern is applied to a conductive layer having a groundline according to FIG. 8.

FIG. 11 is a plan view schematically illustrating another example of theconductive layer having the ground line.

FIG. 12 is a plan view schematically illustrating an example in which adummy pattern is applied to a conductive layer having a ground lineaccording to FIG. 11.

FIG. 13 is a plan view schematically illustrating another example inwhich a dummy pattern is applied to a conductive layer having a groundline according to FIG. 11.

FIG. 14 schematically illustrates a signal return path of an example ofa ground line patterned in an oblique meander shape.

FIG. 15 schematically illustrates a signal return path of an example ofa ground surface patterned in a fill shape.

FIG. 16 schematically illustrates a signal return path of an example ofa ground line patterned in a hatch shape.

FIG. 17 schematically illustrates a corresponding relationship for eachof the positions of the signal lines of examples of ground linespatterned in the oblique meander shape and ground line patterned in thehatch shape.

FIG. 18 schematically illustrates a simulation result of characteristicimpedance for each of the positions of the signal line of the examplesof ground lines patterned in the oblique meander shape and the examplesof ground lines patterned in the hatch shape.

Throughout the drawings and the detailed description, the same referencenumerals refer to the same elements. The drawings may not be to scale,and the relative size, proportions, and depiction of elements in thedrawings may be exaggerated for clarity, illustration, and convenience.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader ingaining a comprehensive understanding of the methods, apparatuses,and/or systems described herein. However, various changes,modifications, and equivalents of the methods, apparatuses, and/orsystems described herein will be apparent to one of ordinary skill inthe art. The sequences of operations described herein are merelyexamples, and are not limited to those set forth herein, but may bechanged as will be apparent to one of ordinary skill in the art, withthe exception of operations necessarily occurring in a certain order.Also, descriptions of functions and constructions that are well known toone of ordinary skill in the art may be omitted for increased clarityand conciseness.

The features described herein may be embodied in different forms, andare not to be construed as being limited to the embodiments describedherein. Rather, the embodiments described herein have been provided sothat this disclosure will be thorough and complete, and will convey thefull scope of the disclosure to one of ordinary skill in the art.

Throughout the specification, it is to be understood that when anelement, such as a layer, region or substrate, is referred to as being“on,” “connected to,” or “coupled to” another element, it can bedirectly “on,” “connected to,” or “coupled to” the other element orother elements intervening therebetween may be present. In contrast,when an element is referred to as being “directly on,” “directlyconnected to,” or “directly coupled to” another element, other elementsor layers intervening therebetween cannot be present. Like numeralsrefer to like elements throughout. As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items.

Although terms such as “first,” “second,” and “third,” may be usedherein to describe various members, components, regions, layers and/orsections, these members, components, regions, layers, or sections arenot to be limited by these terms. These terms are only used todistinguish one member, component, region, layer or section from anothermember, component, region, layer or section. Thus, a first member,component, region, layer or section discussed in embodiments below mayalso be referred to as a second member, component, region, layer orsection without departing from the teachings of the embodiments.

Spatially relative terms such as “above,” “upper,” “below,” and “lower”may be used herein for ease of description to describe one element'srelationship to one or more other elements as shown in the figures. Itis to be understood that the spatially relative terms are intended toencompass different orientations of the device in use or operation inaddition to the orientation depicted in the figures. For example, if thedevice in the figures is turned over, elements described as being“above” another element or being an “upper” element will then be “below”the other element or will be a “lower” element. Thus, the term “above”can encompass both the above and below orientations depending on aparticular direction of the figures. The device may also be oriented inother ways (for example, rotated 90 degrees or at other orientations)and the spatially relative descriptors used herein are to be interpretedaccordingly.

The terminology used herein describes various embodiments only and isnot to be used to limit the present disclosure. As used herein, thesingular terms “a,” “an,” and “the” are intended to include the pluralterms as well, unless the context clearly indicates otherwise. Further,as used herein, the terms “include,” “comprises,” and “have” specify thepresence of stated features, numbers, operations, members, elements,and/or combinations thereof, but do not preclude the presence oraddition of one or more other features, operations, members, elements,and/or combinations thereof.

Hereinafter, embodiments will be described with reference to schematicdiagrams. In the drawings, due to manufacturing techniques and/ortolerances, for example, modifications of the shape shown may beestimated. Thus, the embodiments described herein are not to beconstrued as being limited to the shapes of regions shown herein, butare to be construed as including changes in shapes that occur duringmanufacturing. The features of the embodiments described herein may becombined in various ways as will be apparent to one of ordinary skill inthe art.

As described above, in accordance with an industry trend towardproducing thinner electronic products, the thickness of an insulatinglayer included in a circuit board tends to be reduced. The reduction inthe thickness of the insulating layer may in turn reduce thecharacteristic impedance of the circuit board.

To maintain the impedance of the circuit board, the line width or thethickness of a signal line included in the circuit board may beadjusted. However, such modification may cause transmission loss orrestrict the layout for a circuit element.

In order to prevent the transmission loss, according to an example ofthe present disclosure, the impedance of the circuit board may bematched by varying a design of the ground rather than a design of thesignal line.

According to another example, a new ground pattern structure capable ofsignificantly reducing a change in characteristic impedance values of acircuit board that may result from changing the position of a signalline is provided.

According to another example, a ground line of the circuit board may bepatterned so that the characteristic impedance of the circuit boardremain constant regardless of the position of a signal line formed overthe ground line.

Although the examples described below have a variety of configurations,other configurations are possible as will be apparent to one of ordinaryskill in the art.

Electronic Component

FIG. 1 schematically illustrates an example of a circuit board used inan electronic component. Referring to the example illustrated in FIG. 1,the electronic component corresponds to a camera module, and the circuitboard corresponds to a circuit board 300 for the camera module. Thecircuit board 300 is disposed below a lens assembly 1, a VCM assembly 2,an IR filter 3, and a sensor 4, and is disposed above an ISR module 5.However, FIG. 1 illustrates only an example of the circuit board 300,and the components may be disposed in a different arrangement andconfiguration from that described above in another example. In addition,other components may be further added or substituted.

The circuit board 300 for the camera module includes a signaltransmitting part 320 and a ground part 330. In the illustrated example,the signal transmitting part 320 provides a control signal to the VCMassembly 2, the sensor 4, the ISP module 5, and the like, and includesat least one signal line 321. The signal line 321 serves the purpose ofsupporting a mobile industry processor interface (MIPI). In thisexample, the signal line 321 is configured by four pairs of lanes andone clock line; however, the arrangement of the signal line 321 is notlimited thereto. For instance, in another example, the signal line 321may be configured by a single signal line. The ground part 330 providesa ground to the signal line 321 of the signal transmitting part 320, andincludes a plurality of conductive patterns 331, 332, and 333.

FIG. 2 illustrates an example of a ground part 330 according to thecircuit board illustrated in FIG. 1. In FIG. 2, the ground part 330includes a plurality of conductive patterns 331, 332, and 333. Referringto the example illustrated in FIG. 2, a first conductive pattern 331 ofthe ground part 330 is formed on a portion at which the signal line 321is in contact with the VCM assembly 2. In addition, a second conductivepattern 332 of the ground part 330 is formed below a middle point of thesignal line 321. In addition, a third conductive pattern 333 of theground part 330 is formed at a portion in which the signal line 321 isconnected to a control signal line 313 of a sensor mounting part 310 tobe described below.

The circuit board 300 for the camera module further includes the sensormounting part 310 for mounting the sensor 4, as illustrated in FIG. 1.Referring to FIG. 1, the sensor mounting part 310 includes a sensormounted portion 311, a fourth conductive pattern 312, and the controlsignal line 313. Further, the circuit board 300 for the camera moduleincludes a connector part 340, as illustrated in FIG. 1. The connectorpart 340 provides a connection with the outside and may be formed of arigid material to provide structural support; however, the configurationof the circuit board 300 is not limited thereto.

The circuit board 300 for the camera module may accomplish an impedancematching by the sensor mounting part 310, the signal transmitting part320, the ground part 330, and the like disposed as described above. Forinstance, in an example in which shapes of the conductive patternsincluded in the sensor mounting part 310 and/or the ground part 330 areimplemented in a ground pattern shape to be described below, adifference in the values of characteristic impedances resulting frompositioning the signal line of the signal transmitting part 320 indifferent locations may be significantly reduced while maintaining ahigh characteristic impedance for the circuit board 300. A descriptionthereof will be provided below.

Although FIGS. 1 and 2 describe an example of a circuit board in whichthe electronic component is a camera module, the circuit board describedin the present disclosure is not necessarily applied only to a cameramodule. Rather, the circuit board may be applied to various otherelectronic components that include a circuit board. Further, indescribing a range of an upper concept, the circuit board may also beapplied to other electronic devices including a circuit board.

Examples of other electronic components that include a circuit boardinclude an adapter, an antenna, a cellular FEM, a digital tuner, an LEDlighting power, a server power, a TV power, a vibration, a wireless LAN,a wireless power transfer, and like, but the examples are not limitedthereto. A circuit board may be applied to other electronic components.

Examples of electronic devices including a circuit board include asmartphone, a personal digital assistant, a digital video camera, adigital still camera, a network system, a computer, a monitor, a tablet,a laptop, a netbook, a television, a video game console, a smart watch,and the like, but the examples are not limited thereto. A circuit boardmay be applied to other electronic devices.

Circuit Board

FIGS. 3A and 3B are cross-sectional views schematically illustrating anexample of a circuit board 100A. Referring to the example illustrated inFIGS. 3A and 3B, the circuit board 100A includes a first conductivelayer 120 and a second conductive layer 130 with a first insulatinglayer 110 disposed therebetween. The circuit board 100A may be formed ofany configuration, provided that the configuration includes the firstconductive layer 120 and the second conductive layer 130 with the firstinsulating layer 110 disposed therebetween. The circuit board 100Aaccording to the illustrated example may be classified into a microstripcircuit board.

The first insulating layer 110 may include a dielectric medium having asuitable dielectric constant to insulate the first conductive layer 120from the second conductive layer 130. The first insulating layer 110 mayhave a predetermined height h according to a size of an electronicproduct to which the first insulating layer 110 is applied. A materialthat forms the first insulating layer 110 may be selected withoutlimitation as long as the material is an insulating material. Forexample a thermosetting resin such as an epoxy resin, a thermoplasticresin such as polyimide, or a resin having a reinforcement material suchas a glass fiber or an inorganic filler impregnated therein, such as apre-preg, Ajinomoto build-up film (ABF), FR-4, a bismaleimide triazine(BT) resin, or the like may be used, but the material of the firstinsulating layer 110 is not limited thereto. The first insulating layer110 may also include therein a metal having excellent rigidity andthermal conductivity disposed therein. For example, as the metaldisposed in the first insulating layer 110, a Fe-Ni based alloy may beused, and Cu plating may also be formed on the surfaces of the Fe-Nibased alloy. However, the composition of the first insulating layer 110is not limited thereto. In addition to the metal alloy, glasses,ceramics, plastics, and the like may be disposed as particles, fibers,and the like within the first insulating layer 110.

Referring to FIG. 3A, the first conductive layer 120 includes signallines 121 and 122. The first conductive layer 120 may serve as thesignal transmitting part of the circuit board. The signal lines 121 and122, which are configured to transmit various signals, for example, acontrol signal, and the like, may be implemented with a pair of signallines 121 and 122 that are spaced apart from each other by apredetermined distance S while simultaneously having a predeterminedwidth W, as illustrated in FIG. 3A. The pair of signal lines 121 and 122may be, for example, two lanes supporting a mobile industry processorinterface (MIPI), but are not limited thereto. While two signal lines121 and 122 are illustrated in FIG. 3A, the first conductive layer 120may include more than two signal lines. Alternatively, the firstconductive layer 120 may include only one signal line 121, asillustrated in FIG. 3B. The signal lines 121 and 122 may include atleast one material selected from silver (Ag), palladium (Pd), aluminum(Al), nickel (Ni), titanium (Ti), gold (Au), copper (Cu), platinum (Pt),and the like having excellent conductivity, or a mixture of at least twomaterials thereof. The signal lines 121 and 122 may be formed by a knownmethod. For example, the signal lines 121 and 122 may be formed byelectro copper plating, electroless copper plating, or the like.According to an example, the signal lines 121 and 122 are formed using achemical vapor deposition (CVD) method, a physical vapor deposition(PVD) method, a sputtering method, a subtractive method, an additivemethod, a semi-additive process (SAP), a modified semi-additive process(MSAP), or the like, but the method is not limited thereto.

The second conductive layer 130 may include a ground line 131. That is,the second conductive layer 130 may serve as the ground part of thecircuit board. The ground line 131 serves the purpose of providinggrounds of a variety of signals of the signal lines 121 and 122 andprovides return paths of various signals at the same time. Theconfiguration of the ground line 131 will be described below. The groundline 131 may include at least one material selected from silver (Ag),palladium (Pd), aluminum (Al), nickel (Ni), titanium (Ti), gold (Au),copper (Cu), platinum (Pt), and the like having excellent conductivity,or a mixture of at least two materials thereof, similar to the signallines 121 and 122. The ground line 131 may also be formed by a knownmethod, such as electro copper plating, electroless copper plating, orthe like. For example, the ground line 131 may be formed using achemical vapor deposition (CVD) method, a physical vapor deposition(PVD) method, a sputtering method, a subtractive method, an additivemethod, a semi-additive process (SAP), a modified semi-additive process(MSAP), or the like, but is not limited thereto.

In the circuit board 100A according to an example, an E-field and anH-field may be formed between the signal lines 121 and 122 of the firstconductive layer 120 and the ground line 131 of the second conductivelayer 130. In this case, characteristic impedance may be influenced bythe formed E-field and H-field.

FIGS. 4A and 4B are cross-sectional views schematically illustratingadditional examples of circuit boards 100B. Referring to FIGS. 4A and4B, a circuit board 100B includes a first conductive layer 120 and asecond conductive layer 130 with a first insulating layer 110 disposedtherebetween. In addition, a second insulating layer 140 is disposedbetween the first conductive layer 120 and a third conductive layer 150.The circuit board 100B according to this example may be modified to havedifferent configurations, provided that the circuit board 10B includes afirst conductive layer 120, a second conductive layer 130, and a thirdconductive layer 150 with a first insulating layer 110 disposed betweenthe first and second conductive layers 120, 130 and a second insulatinglayer 140 disposed between the first and the third conductive layers120, 150. A circuit board 100B having such a configuration may beclassified as a stripline circuit board.

The first insulating layer 110 includes a dielectric medium having adielectric constant as described above, and has a predetermined heighth1 determined according to the size of the electronic product to whichthe first insulating layer 110 is applied. A material for the firstinsulating layer 110 may be selected without limitation as long as thematerial is an insulating material. For example a thermosetting resinsuch as an epoxy resin, a thermoplastic resin such as polyimide, or aresin having a reinforcement material such as a glass fiber or aninorganic filler impregnated therein, such as a pre-preg, Ajinomotobuild-up film (ABF), FR-4, a bismaleimide triazine (BT) resin, or thelike may be used, but the material of the first insulating layer 110 isnot limited thereto. The first insulating layer 110 may also include ametal having excellent rigidity and thermal conductivity disposedtherein as particles. A Fe-Ni based alloy may be, for example, used toform particles, and Cu plating may also be formed on the surfaces on theFe-Ni based alloy particles. In addition, glasses, ceramics, plastics,and the like may be also disposed in the first insulating layer 110 ordisposed in the first insulating layer 110 instead of the metalparticles.

The second insulating layer 140 may include a dielectric medium having adielectric constant similar to the first insulating layer 110, and mayhave a height h2 predetermined according to a size of a product to whichthe second insulating layer 140 is applied. A material of the secondinsulating layer 140 may also be selected without limitation as long asthe material is an insulating material. For example, a thermosettingresin such as an epoxy resin, a thermoplastic resin such as polyimide,or a resin having a reinforcement material such as a glass fiber or aninorganic filler impregnated therein, such as a pre-preg, Ajinomotobuild-up film (ABF), FR-4, a bismaleimide triazine (BT) resin, or thelike may be used, but the material of the second insulating layer 140 isnot limited thereto. The second insulating layer 140 may also have ametal having excellent rigidity and thermal conductivity disposedtherein. According to an example, as the metal, a Fe-Ni based alloy maybe used, and Cu plating may also be formed on the surface on the Fe-Nibased alloy. Besides the metal, other materials such as glasses,ceramics, plastics, and the like may be disposed in the secondinsulating layer 140.

Referring to FIG. 4A, the first conductive layer 120 includes signallines 121 and 122 as described above. That is, the first conductivelayer 120 may serve as the signal transmitting part of the circuitboard. The signal lines 121 and 122 may transmit various signals, forexample, a control signal, and the like, and may include a pair ofsignal lines 121 and 122 that are spaced apart from each other by apredetermined distance S while having a predetermined width W at thesame time, as illustrated in FIG. 4A. The pair of signal lines 121 and122 may be, for example, two lanes supporting a mobile industryprocessor interface (MIPI), but are not limited thereto. In anotherexample, however, the first conductive layer 120 may include more thantwo signal lines. Alternatively, the first conductive layer 120 mayinclude only a single signal line 121, as illustrated in FIG. 4B. Thesignal lines 121 and 122 may include at least one material selected fromsilver (Ag), palladium (Pd), aluminum (Al), nickel (Ni), titanium (Ti),gold (Au), copper (Cu), platinum (Pt), and the like having excellentconductivity, or a mixture of at least two materials thereof. The signallines 121 and 122 may be formed by a known method. For example, thesignal lines 121 and 122 may be formed by electro copper plating,electroless copper plating, or the like. According to an example, thesignal lines 121 and 122 may be formed using a chemical vapor deposition(CVD) method, a physical vapor deposition (PVD) method, a sputteringmethod, a subtractive method, an additive method, a semi-additiveprocess (SAP), a modified semi-additive process (MSAP), or the like, butthe method of forming the signal lines 121 and 122 is not limitedthereto.

The second conductive layer 130 may include a ground line 131 asdescribed above. That is, the second conductive layer 130 may serve asthe ground part of the circuit board. The purpose of the ground line 131is to provide grounds of a variety of signals of the signal lines 121and 122 and provide return paths of the variety of signals at the sametime. A configuration of the ground line 131 will be described below.The ground line 131 may include at least one material selected fromsilver (Ag), palladium (Pd), aluminum (Al), nickel (Ni), titanium (Ti),gold (Au), copper (Cu), platinum (Pt), and the like having excellentconductivity, or a mixture of at least two materials thereof, similar tothe signal lines 121 and 122. The ground line 131 may be formed by aknown method. For example, the ground line 131 may be formed by electrocopper plating, electroless copper plating, or the like. According to anexample, the ground line 131 may be formed using a chemical vapordeposition (CVD) method, a physical vapor deposition (PVD) method, asputtering method, a subtractive method, an additive method, asemi-additive process (SAP), a modified semi-additive process (MSAP), orthe like, but the method of forming the ground line 131 is not limitedthereto.

The third conductive layer 150 may include a ground line similar to thesecond conductive layer 120. That is, the third conductive layer 150 mayalso serve as the ground part. The purpose of the ground line is also toprovide grounds of various signals of the signal lines 121 and 122 andprovide return paths of the various signals at the same time. Aconfiguration of the ground line will be described below. The groundline may similarly include at least one material selected from silver(Ag), palladium (Pd), aluminum (Al), nickel (Ni), titanium (Ti), gold(Au), copper (Cu), platinum (Pt), and the like having excellentconductivity, or a mixture of at least two materials thereof. The groundline may be formed by a known method, such as electro copper plating,electroless copper plating, or the like. According to an example, theground line may be formed using a chemical vapor deposition (CVD)method, a physical vapor deposition (PVD) method, a sputtering method, asubtractive method, an additive method, a semi-additive process (SAP), amodified semi-additive process (MSAP), or the like, but the method isnot limited thereto.

In the circuit board 100B according to another example, an E-field andan H-field may be formed between the signal lines 121 and 122 of thefirst conductive layer 120 and the ground line 131 of the secondconductive layer 130, and between the signal lines 121 and 122 of thefirst conductive layer 120 and the ground line 131 of the secondconductive layer 130. In this example, characteristic impedance may beinfluenced by the formed E-field and H-field.

FIG. 5 is a plan view schematically illustrating an example of thesecond conductive layer 130. Referring to FIG. 5, the second conductivelayer 130 includes the ground line 131, which is a conductive path inwhich a plurality of conductive patterns are connected to each other.The ground line 131 includes an area A corresponding to an area wherethe signal line 121 is provided. According to this example, in thecorresponding area A, the impedance of the circuit board is matched by apattern design of the ground line 131, rather than by forming the signalline 121 according to a pattern design. In FIG. 5, only one signal line121 is illustrated for convenience, but the number of signal lines inthe corresponding area A is not limited thereto. For example, aplurality of signal lines may be provided in the corresponding area A.Further, the signal line 121 may be repositioned within thecorresponding area A or be bent or curved in the corresponding area A.

In this example, unit patterns having an opened curve shape are disposedon an edge portion B of the ground line 131, and inner unit patternshaving an obliquely inclined shape are disposed between the outer unitpatterns having the opened curve shape disposed along the edge portionB. The above-mentioned unit patterns are connected to each other to forma return path for a variety of signals transferred through the signalline 121. In this example, the ground line 131 is thus patterned in anoblique meander shape. Thereby, a difference of values of characteristicimpedances that may result from changing the position of the signal linein the corresponding area A may be significantly reduced whilemaintaining the characteristic impedance of the circuit board.

As described above, the impedance characteristics of the circuit boardis typically determined by a line width W and a thickness T of thesignal line 121, a height between the signal line 121 and the groundline 131, a dielectric constant of a medium configuring the insulatinglayer 110, and the like. However, in accordance with a trend towardproducing thinner electronic products, the thickness T of the insulatinglayer 110 may be reduced when a circuit board is being designed. Thus,the impedance of the circuit board may become reduced beyond a desiredvalue. To ameliorate the reduction of impedance, the line width W or thethickness T of the signal line 121 may be adjusted. However, in theevent that the line width W or the thickness T of the signal line 121 isadjusted to control the impedance of the circuit board, a transmissionloss may inevitably occur. Further, when the line width W and thethickness T of the signal line 121 are adjusted to control theimpedance, the freedom to design a layout of circuit elements issignificantly compromised.

According to an example, a method of matching impedance of the circuitboard by varying a design of the ground line 131, rather than a designof the signal line 121, is provided. In this example, to significantlyreduce the difference in the characteristic impedances resulting fromchanging the position of a signal line while maintaining the highcharacteristic impedance of a circuit board, the ground line 131 ispatterned in an oblique meander shape. Because forming the ground line131 in an oblique meander shape allows the return path of the groundline 131 to be longer than the return path of the signal line 121, theground line 131 may exhibit high impedance characteristics. In addition,because a pattern shape of the corresponding ground line 131 isconstantly maintained regardless of the exact position of the signalline 121 in the corresponding area A, the difference of thecharacteristic impedances that results from repositioning the signalline 121 within the corresponding area A may be significantly reduced.Therefore, the impedance mismatching may be substantially eliminated inthe corresponding area A of a circuit board.

The unit patterns having an opened curve shape that are disposed on theedge portion B of the ground line 131 may serve to connect the innerunit patterns disposed therebetween to each other. According to anexample, because the outer unit patterns having the opened curve shapeare disposed along all edge portions (a top, a bottom, a left, and aright) of the ground line 131, the space utility of the ground line 131may be increased by forming the unit patterns having an obliquelyinclined shape. As a result, a ground pattern 131 having a longer paththan the signal line 121 may be obtained. Referring to FIG. 5, to form aground pattern 131 having the elongated path, the ground pattern 131includes a pattern area formed in a meander shape so that the conductivepath of the ground pattern 131 passes across the signal line 121 severaltimes in a plan view of the circuit board. The precise shape of the unitpatterns having the opened curve shape is not limited to the illustratedexample, and a different shape may be used as long as the unit patternshaving the opened curve shape is disposed on the edge portion B toconnect the unit patterns having the stripe shape disposed therebetweento each other in an oblique angle with respect to the signal line 121.

Since the unit patterns having the obliquely inclined shape disposedbetween the unit patterns having the opened curve shape disposed on theedge portion B have high space utility, the unit patterns having theobliquely inclined shape allows the ground line 131 to have a longerpath. Accordingly, high impedance characteristics may be implemented. Inthis example, the unit patterns having the obliquely inclined shape havea constant line width W, and also have a constant interval Ltherebetween. Further, the unit patterns having the obliquely inclinedshape may include a plurality of conductive stripes that are alignedalong substantially the same direction to each form substantially thesame angle with the signal line 121. Accordingly, the pattern shape ofthe unit patterns having the obliquely inclined shape is constantlymaintained in the corresponding area A regardless of the position of thesignal line 121. Thus, even when the signal line is repositioned to adifferent location of the corresponding area A, the impedances may bemaintained to be substantially the same.

A value for the line width W or the interval L of the unit patternshaving the obliquely inclined shape is not particularly limited, and maybe designed to obtain the desired impedance. For example, the impedanceof the circuit board may be decreased by increasing the line width W, asneeded. Similarly, the value of a gradient of the unit patterns havingthe obliquely inclined shape is also not particularly limited, and anyunit patterns having the obliquely inclined shape may be used as long asthe unit patterns are constantly and obliquely inclined.

FIGS. 6 and 7 are plan views schematically illustrating examples ofground lines in which dummy patterns 132 of various configurations areapplied to the second conductive layer 130. In general, in a case inwhich an interval of the ground line 131 is increased, the impedance ofthe circuit board may be increased; however, an electromagneticinterference (EMI) emission may occur due to the increased interval. Asa result, the EMI emission may cause interference in other signal lines.Referring to the example illustrated in FIG. 6, a plurality of dummypatterns 132 that are not connected to the ground line 131 are disposedbetween the intervals of the ground line 131. Thus, the EMI emission maybe shielded while maintaining the impedance. Further, because aconductive ratio of the second conductive layer 130 may be adjusted bythe plurality of dummy patterns 132, warpage may also be controlled.

Herein, a layout, a shape, a width, an interval, or the like of thedummy pattern 132 is not limited to the illustrated example, and may bemodified as long as the plurality of dummy patterns 132 do not interferewith an overall layout of the ground line 131. For example, referring anexample illustrated in FIG. 6, a dummy pattern 132 is disposed betweenthe respective intervals of the ground line 131 while the ground line131 forms an oblique meander shape. On the other hand, in FIG. 7, aplurality of dummy patterns 132 are disposed between the respectiveintervals of the ground line 131.

The plurality of dummy patterns 132 may include at least one materialselected from silver (Ag), palladium (Pd), aluminum (Al), nickel (Ni),titanium (Ti), gold (Au), copper (Cu), platinum (Pt), and the likehaving excellent conductivity, or a mixture of at least two materialsthereof. The dummy pattern 132 may be formed by a known method, such aselectro copper plating, electroless copper plating, or the like.According to one example, the dummy pattern 132 is formed using a methodsuch as a chemical vapor deposition (CVD) method, a physical vapordeposition (PVD) method, a sputtering method, a subtractive method, anadditive method, a semi-additive process (SAP), a modified semi-additiveprocess (MSAP), or the like, but the method of forming the dummy pattern132 is not limited thereto.

FIG. 8 is a plan view schematically illustrating another example of thesecond conductive layer 130. In this example, the second conductivelayer 130 includes the ground line 131, which is a conductive path inwhich a plurality of conductive patterns are connected to each other.Further, the ground line 131 includes an area A that corresponds to anarea in which the signal line 121 is provided. Further, in thecorresponding area A, the impedance of the circuit board is matched byforming the ground line 131 according to a pattern design while thesignal line 121 is formed without a pattern design for controlling theimpedance. Only a single signal line 121 corresponding to the groundline 131 is illustrated in FIG. 8 for convenience; however, the numberof signal lines is not limited thereto. For example, there may be aplurality of signal lines, or the signal line 121 may be repositionedwithin the corresponding area A.

Referring to FIG. 8, unit patterns having an opened bracket shape aredisposed along an edge portion B of the ground line 131, and unitpatterns having an obliquely inclined shape that are arranged to from azigzag shape are disposed between the unit patterns having the openedbracket shape. The above-mentioned unit patterns are connected to eachother to form a return path for various signals transferred through thesignal line 121. That is, the ground line 131 according to FIG. 8 ispatterned in a meander shape. Thereby, a difference in thecharacteristic impedance values that results when the position of thesignal line is changed within the corresponding area A may besignificantly reduced while maintaining the desired characteristicimpedance.

The unit patterns having the opened bracket shape disposed on the edgeportion B serve as a type of a connection part that connects the unitpatterns disposed therebetween to each other. In another example, theunit patterns having the opened bracket shape may be disposed on onlysome of the edges (a left and a right) of the ground line 131 in therelation to the drawing. Also, a shape of the unit patterns having theopened bracket shape is not limited to the illustrated example, and adifferent shape may be used as long as the unit patterns having theopened bracket shape may be disposed on the edge portion B to connectthe inner unit patterns having an obliquely inclined shape to form azigzag shape, thereby forming a meander shape conductive path.

Because the inner unit patterns having the obliquely inclined shapedisposed between the outer unit patterns having the opened bracket shapedisposed along the edge portion B increases the space utility of theconductive path in a compact space, the unit patterns having theobliquely inclined shape allow a longer conductive path to be obtainedas the ground line 131. Accordingly, a circuit board with high impedancecharacteristics may be implemented within a compact space. In anexample, unit patterns having an obliquely inclined shape may beobliquely inclined in a constant zigzag shape. The unit patterns havingthe obliquely inclined shape arranged in the zigzag shape may have aconstant line width W, and may also have a constant interval Ltherebetween. As such, because the pattern shape of the unit patternshaving the obliquely inclined shape substantially corresponding to thesignal line 121 is constantly maintained regardless of the position ofthe signal line 121, the difference of the impedances that may resultfrom changing the position of the signal line may be significantlyreduced.

Herein, a value of the line width W or the interval L of the unitpatterns having the obliquely inclined shape is not particularlylimited, and may be designed based on the desired impedance value. Forexample, the impedance may be decreased by increasing the line width W.Further, a value of a gradient of the unit patterns having the obliquelyinclined shape is also not particularly limited, and a different unitpattern having an obliquely inclined shape may be used as long as theunit patterns are constantly and obliquely inclined.

FIGS. 9 and 10 are plan views schematically illustrating additionalexamples of circuit boards in which dummy patterns 132 of various shapesare applied to the second conductive layer 130. In the second conductivelayer 130 according to the illustrated examples, a plurality of dummypatterns 132 that are not connected to the ground line 131 are disposedbetween the intervals of the ground line 131, and the EMI emission maybe shielded while maintaining the impedance. Further, because aconductive ratio of the second conductive layer 130 may be adjusted bythe plurality of dummy patterns 132, warpage of the circuit board mayalso be controlled.

Herein, provided that the plurality of dummy patterns 132 do notinterfere with a layout of the ground line 131 described above, alayout, a shape, a width, an interval, or the like of the dummy pattern132 may be modified. For example, in FIG. 9, one dummy pattern 132 isdisposed between the respective intervals of the ground line 131, and inFIG. 10, a plurality of dummy patterns 132 are disposed between therespective intervals of the ground line 131.

The plurality of dummy patterns 132 may include at least one materialselected from silver (Ag), palladium (Pd), aluminum (Al), nickel (Ni),titanium (Ti), gold (Au), copper (Cu), platinum (Pt), and the likehaving excellent conductivity, or a mixture of at least two materialsthereof. The dummy pattern 132 may also be formed by a known method,such as electro copper plating, electroless copper plating, or the like.For example, the dummy pattern 132 may be formed using a method such asa chemical vapor deposition (CVD) method, a physical vapor deposition(PVD) method, a sputtering method, a subtractive method, an additivemethod, a semi-additive process (SAP), a modified semi-additive process(MSAP), or the like, but the method is not limited thereto.

FIG. 11 is a plan view schematically illustrating another example of asecond conductive layer 130. In this example, the second conductivelayer 130 includes the ground line 131, which is a conductive path inwhich a plurality of conductive patterns are connected to each other toform a return path. Further, the ground line 131 includes an area Acorresponding to an area in which a signal line 121 is provided. In thecorresponding area A, the impedance of the circuit board may be matchedby a pattern design of the ground line 131, not by a pattern design ofthe signal line 121. Further, while a single signal line 121corresponding to the ground line 131 is illustrated in FIG. 11 forconvenience, the number of signal lines is not limited thereto. Forexample, there may be a plurality of signal lines.

Unit patterns having an opened bracket shape are disposed on an edgeportion B of the ground line 131, and unit patterns having a curved waveshape with obliquely inclined portions are disposed between the unitpatterns having the opened bracket shape disposed along the edge portionB. The above-mentioned unit patterns are connected to each other to forma return path for a variety of signals transferred through the signalline 121. That is, the ground line 131 is also patterned in a meandershape. Thereby, a difference in the characteristic impedances resultingfrom changing the position of the signal line may be significantlyreduced while maintaining the characteristic impedance of the circuitboard within a desired range.

The unit patterns having the opened bracket shape disposed on the edgeportion B may similarly serve as a kind of a connection part connectingthe unit patterns disposed therebetween to each other. In this example,the unit patterns having the opened bracket shape are disposed on onlysome edges (a left and a right) of the ground line 131 in relation tothe drawing. However, the shape of the unit patterns having the openedbracket shape is not limited thereto, and unit patterns having adifferent shape may be used as long as the unit patterns having theopened bracket shape are disposed along the edge portion B to connectthe inner unit patterns disposed therebetween.

Because the unit patterns having a curved wave shape disposed betweenthe unit patterns having the opened bracket shape disposed on the edgeportion B have high space utility, the unit patterns having curved waveshape may allow a longer path of the ground line 131 to be implementedin a compact space. Accordingly, high impedance characteristics may beimplemented. In this example, the unit patterns having a curved waveshape include portions that are obliquely inclined with respect to thesignal line 121 such that the conductive path forms a curved zigzagshape. In this example, the unit patterns having the curved zigzag shapehave a constant line width W, and also have a constant interval Ltherebetween. Because the pattern shape of the unit patterns having theobliquely inclined portion is substantially constantly where the signalline 121 overlaps with the ground line 131 regardless of the exactposition of the signal line 121, the impedance values obtained byvarying the position of the signal line in the corresponding area A aresimilar. Thus, a change in the impedance value resulting fromrepositioning the signal line may be significantly reduced.

Similarly, a value for the line width W or the interval L of the unitpatterns having the obliquely inclined shape is not particularlylimited, and may be determined based on the desired impedance value. Forexample, the impedance of the circuit board may be decreased byincreasing the thickness of the line width W. Further, a value of agradient of the inner unit patterns having a curved wave shape havingobliquely inclined portions is also not particularly limited, and unitpatterns having a different shape may be used as long as the unitpatterns exhibit constantly and obliquely inclined portions aligned toconform to the angle of the neighboring unit patterns.

FIGS. 12 and 13 are plan views schematically illustrating additionalexamples of circuit boards in which dummy patterns 132 of various shapesare applied to the second conductive layer 130. In the examples ofsecond conductive layers 130 illustrated in FIGS. 12 and 13, a pluralityof dummy patterns 132 that are not connected to the ground line 131 aredisposed between the intervals of the ground line 131. Thus, the EMIemission may be shielded while maintaining the impedance. Further,because a conductive ratio of the second conductive layer 130 may beadjusted by the plurality of dummy patterns 132, warpage of the circuitboard may also be controlled.

Similarly, as long as the plurality of dummy patterns 132 do notinterfere with an overall layout of the ground line 131 described above,a layout, a shape, a width, an interval, or the like of the dummypattern 132 is not particularly limited. For example, referring to FIG.12, a continuous dummy pattern 132 is disposed between the respectiveintervals of the ground line 131. However, referring to FIG. 13, aplurality of dummy patterns 132 are disposed between the respectiveintervals of the ground line 131.

Similarly, the plurality of dummy patterns 132 may include at least onematerial selected from silver (Ag), palladium (Pd), aluminum (Al),nickel (Ni), titanium (Ti), gold (Au), copper (Cu), platinum (Pt), andthe like having excellent conductivity, or a mixture of at least twomaterials thereof. The dummy pattern 132 may be formed by a knownmethod, such as electro copper plating, electroless copper plating, orthe like. According to an example, the dummy pattern 132 may be formedusing a method such as a chemical vapor deposition (CVD) method, aphysical vapor deposition (PVD) method, a sputtering method, asubtractive method, an additive method, a semi-additive process (SAP), amodified semi-additive process (MSAP), or the like, but the method ofobtaining the dummy pattern 132 is not limited thereto.

Although FIGS. 5 through 13 illustrate various examples of the secondconductive layer 120, the above-mentioned illustrations are not appliedto only the second conductive layer 120, but may also be applied to thethird conductive layer 150. That is, a ground line of the thirdconductive layer 150 may also be a conductive path in which a pluralityof conductive patterns are connected to each other to form a meandershape, and may have an area in which the signal line 121 is provided. Inaddition, unit patterns having an opened curve shape or opened bracketshape may be disposed on an edge portion of the ground line, and innerunit patterns having an obliquely inclined shape, obliquely inclinedshapes arranged in a zigzag shape, or a curved wave shape, may bedisposed between the outer unit patterns having the opened curve shapeor opened bracket shape disposed along the edge portion. Theabove-mentioned unit patterns may be connected to each other to formreturn paths for a variety of signals transferred through the signalline 121. That is, to significantly reduce a difference of values ofcharacteristic impedances for each of positions of the signal line whilemaintaining high characteristic impedance, the ground line 131 may bepatterned, for example, in an oblique meander shape or other repetitiveshape. In addition, the third conductive layer 150 may also includedummy patterns of various shapes, and for example, a plurality of dummypatterns which are not connected to the ground line may be disposedbetween the intervals of the ground line. An additional detaileddescription refers to the contents described with respect to FIGS. 5through 13.

FIG. 14 schematically illustrates a signal return path RP of the groundline 131 patterned in an oblique meander shape. Referring to FIG. 14,because the signal return path RP of the ground line 131 patterned inthe oblique meander shape is meanderingly moved in a diagonal linedirection along one path, the signal return path RP may have a pathlonger than the signal line 121. Further, the return path RP includesseveral portions in which the ground line passes across the signal line121 in a plan view of the circuit board. The current directions 151, 152of the ground line as the ground line passes across the signal line 121alternate toward two different sides of the signal line 121. In theexample illustrated in FIG. 14, the inner conductive patterns includeobliquely inclined stripes that are arranged parallel to each other. Thecurrent direction 151 in an obliquely inclined stripe is opposite to thecurrent direction 152 in an adjacent obliquely inclined stripe such thatthe current directions 151, 152 form a 180 degree angle with respect toeach other.

As noted above, in accordance with the trend for producing slenderelectronic products, the thickness of the insulating layer may bereduced, thereby making it difficult to maintain the characteristicimpedance of a circuit board. As such, in a case in which the signalreturn path RP is implemented to be longer, since a compensation for animpedance decrease caused by the decrease in the thickness of theinsulating layer is possible, the characteristic impedance of thecircuit board may be more effectively maintained.

FIG. 15 schematically illustrates a signal return path RP of a groundsurface 431 patterned in a fill shape. Referring to FIG. 15, the signalreturn path RP of the ground surface 431 patterned in the fill shape maybe moved along various paths. As a result, it may be difficult tocontrol the signal return path RP. Further, because the ground surface431 patterned in the fill shape has the signal return path RP shorterthan the ground line 131 patterned in the oblique meander shape, acompensation for an impedance decrease caused by the decrease in thethickness of the insulating layer is expected to be insufficient toproduce a circuit board having the desired impedance.

FIG. 16 schematically illustrates a signal return path RP of a groundline 531 patterned in a hatch shape. Referring to FIG. 16, the signalreturn path RP of the ground line 531 patterned in the hatch shape mayalso be moved along various paths. As a result, it may be difficult tocontrol the signal return path RP. Further, because the ground line 531patterned in the hatch shape may have the signal return path RP longerthan the ground surface 431 patterned in the fill shape, but may havethe signal return path RP shorter than the ground line 131 patterned inthe oblique meander shape, a compensation for an impedance decreasecaused by the decrease in the thickness of the insulating layer isexpected to be insufficient in comparison to the ground line 131patterned in the oblique meander shape illustrated in FIG. 14.

FIG. 17 schematically illustrates a corresponding relationship for eachpositions of the signal line of the ground line patterned in an obliquemeander shape and the ground line patterned in the hatch shape. In thisexample, “the corresponding relationship for each of the positions” ofthe signal line may be determined in relation to “a case in which thesignal lines are disposed in parallel with each other”. Referring toFIG. 17, it may be seen that the ground line patterned in the obliquemeander shape has corresponding pattern shapes which are constantlymaintained in any case of a position 1 and a position 2 of the signalline. In addition, referring to FIGS. 14 and 17, it may be seen that thecorresponding return path is constantly maintained in any case of theposition 1 and the position 2 of the signal line. On the other hand, itmay be seen that the ground line patterned in the hatch shape has thecorresponding pattern shapes which are different depending on theposition 1 and the position 2 of the signal line. In addition, referringto FIGS. 16 and 17, it may be seen that the corresponding return pathsvaries depending on the position 1 and the position 2 of the signalline. That is, it may be seen that, because a ground line patterned inan oblique meander shape may implement the signal return path to belonger, a circuit board with high impedance may be obtained. Further,with the oblique meander shape, because the pattern shape and the signalreturn path may be constantly maintained with respect to the signalline, a change in impedance resulting from different positions of thesignal line may be significantly reduced. Therefore, it may be seen thatthe impedance may be effectively matched by varying a design of theground, and not in the signal line.

FIG. 18 schematically illustrates a simulation result of characteristicimpedance for each of the positions of the signal line of a ground linepatterned in an oblique meander shape and a ground line patterned in ahatch shape. In the graph, a position 1 and a position 2 refer to theposition 1 and the position 2 of the signal line illustrated in FIG. 17.Referring to FIG. 18, it may be seen that the ground line patterned inthe oblique meander shape has characteristic impedance over timebasically maintained to be higher than the ground line patterned in thehatch shape. In addition, it may be seen that the ground line patternedin the oblique meander shape has a difference of the characteristicimpedances over time of about 10 or less at both the position 1 and theposition 2. For example, it may be seen that the difference of thecharacteristic impedances of the position 1 and the position 2 is merelyabout 0.010 at 1.06 ns. On the other hand, a case in which thedifference of the characteristic impedances over time of the position 1and the position 2 is large to an extent as to exceed 10 exists in theground line patterned in the hatch shape. For example, it may be seenthat the difference of the characteristic impedances of the position 1and the position 2 is significantly large to the extent of about 20 at1.06 ns. That is, it may be supported by a simulation result that,because the ground line patterned in the oblique meander shape mayimplement the signal return path to be longer, high impedance may beimplemented, and since it may constantly maintain the pattern shape andthe signal return path corresponding to a signal line, an impedancedifference according to the positions of the signal line may besignificantly reduced.

As set forth above, according to the embodiments in the presentdisclosure, the new ground pattern structure capable of significantlyreducing the difference of the values of characteristic impedances foreach of the positions of the signal line while maintaining highcharacteristic impedance, and the circuit board using the same, may beprovided.

The expression that “components are constant” as used in the presentdisclosure refers to a case in which there are many components and thecomponents are formed substantially the same as each other or to a casein which the components are exactly the same as each other. Theexpression that the “components are constant” takes into account anerror range that may inevitably occur during a process of forming thecomponents. Further, the expression that the “components are constant”takes into account of a case in which the components are generally thesame as each other but only a specific portion is slightly different byintentionally varying only the specific portion in order to avoid thescope of the present disclosure.

In the present disclosure, terms “first”, “second”, and the like, areused to distinguish one component from another component, and do notlimit a sequence and/or importance, and the like, of the correspondingcomponents. In some cases, a first component may be named a secondcomponent, and a second component may also be similarly named a firstcomponent, without departing from the scope of the present disclosure.

The term “example” as used in the present disclosure does not refer to asingle same example, but is provided in order to emphasize and describedifferent unique features. However, the above suggested examples may beimplemented to be combined with a feature of another example. Forexample, even though particulars described in a specific example are notdescribed in another example, it may be understood as a descriptionrelated to another example unless described otherwise.

While this disclosure includes specific examples, it will be apparent toone of ordinary skill in the art that various changes in form anddetails may be made in these examples without departing from the spiritand scope of the claims and their equivalents. The examples describedherein are to be considered in a descriptive sense only, and not forpurposes of limitation. Descriptions of features or aspects in eachexample are to be considered as being applicable to similar features oraspects in other examples. Suitable results may be achieved if thedescribed techniques are performed in a different order, and/or ifcomponents in a described system, architecture, device, or circuit arecombined in a different manner, and/or replaced or supplemented by othercomponents or their equivalents. Therefore, the scope of the disclosureis defined not by the detailed description, but by the claims and theirequivalents, and all variations within the scope of the claims and theirequivalents are to be construed as being included in the disclosure.

What is claimed is:
 1. A circuit board comprising: a first conductivelayer; a second conductive layer; and an insulating layer disposedbetween the first conductive layer and the second conductive layer,wherein the first conductive layer comprises a signal line, and thesecond conductive layer comprises a ground line electrically separatedfrom the signal line, wherein the ground line includes a pattern area ina corresponding area provided with the signal line and an outer areasurrounding the pattern area and being connected to the pattern area,and wherein inner unit patterns of the pattern area are oblique to thesignal line, and outer unit patterns of the pattern area are connectedto the inner unit patterns of the pattern area.
 2. The circuit board ofclaim 1, wherein the outer area connects to the pattern area in tworegions.
 3. The circuit board of claim 1, wherein the outer areaconnects to the pattern area via the outer unit patterns.
 4. The circuitboard of claim 1, wherein a portion of the outer unit patterns issubstantially parallel to the signal line.
 5. The circuit board of claim1, wherein a portion of the outer unit patterns is substantiallyperpendicular to the signal line.
 6. The circuit board of claim 1,wherein a portion of the outer unit patterns is substantially parallelto the signal line, and another portion of the outer unit patterns issubstantially perpendicular to the signal line.
 7. The circuit board ofclaim 1, wherein a shape of the inner unit patterns under the signalline is substantially the same regardless of a position of the signalline within the corresponding area.
 8. The circuit board of claim 1,wherein the second conductive layer further comprises dummy patterns,and the dummy patterns are not connected to the ground line.